It is well known that liquid disinfection agents can be sprayed as finely divided droplets, for example to disinfect items or air of a room contaminated with harmful aerosols. In addition, the beneficial effects of vapors or aerosol mists consisting of finely divided water or oil droplets have also long been known. In conventional sauna or steam baths, water or an aqueous emulsion containing a small amount of essential oils is evaporated. The hot steam cools down in the sauna cabinet and condenses to form mist droplets. A disadvantage of generating mist by evaporating water or an aqueous oil emulsion lies in the high temperature of the generated mist. While the stimulating effect of the hot mist can be vital for certain applications, conventional sauna and steam baths still suffer from the disadvantage that the circulation of the bather is severely challenged, and thus saunas and steam baths are contra-indicated for many groups of people. Thus, it has been suggested that aqueous solutions or emulsions be atomized at lower temperatures, typically at temperatures below 35° C. or 40° C., preferably at temperatures in a temperature range of 22-28° C. The stress on the circulation of the person to be treated would be reduced compared with conventional sauna or steam baths.
In the international patent application WO 00/44331 A1 a whole body mist bath device and a method for administering a whole body mist bath are described, wherein a mist bath is generated at temperatures below 35° C. To this end, a liquid is compressed to a pressure of more than 100 bar and then expelled through a nozzle in an explosive manner into a treatment cabinet so that on being expelled into the cabinet, the liquid is atomized into many small droplets of liquid due to its high internal pressure. In WO 00/4433 A1 it has already been proposed that aqueous salt solutions or oils with vitamin supplements or essential additives could be used to generate a mist. If a mist is to be produced from two different liquids, according to WO 00/44331, two separate nebulizers are used. In the nebulizers described in that document, a compression volume in the form of a hollow cylinder with a closable opening is provided which is connected via a line to a high pressure pump which delivers the liquid to be nebulized.
In the international patent application WO 2009/087053 A1 a method and a device for atomizing fluids is described, in particular for generating a therapeutically effective aerosol in a treatment area, wherein an aerosol generator is used which pressurizes the fluid to be atomized and which expels it at a flow rate in the range 50-300 m/s through at least one discharge opening in the form of small particles into a treatment area. In one embodiment of the device described in WO 2009/087053, the fluid to be atomized is disposed in a cartridge that comprises at least one discharge opening for atomizing fluid and a movable piston that can be moved by means of a drive means. The movable piston exerts a pressure on the fluid in the cartridge such that the fluid is dispensed through the discharge opening at the required flow rate of 50-300 m/s in the form of a finely divided mist of liquid.
One of the disadvantages of the known devices described above, however, is that the particles of liquid are generated with a relatively broad size distribution. Typically, the aerosol mist contains a mixture of particles with a diameter from a few nanometers to several micrometers. However, many applications for aerosols require and desire particle sizes in the sub-micrometer range. If in such cases particles are also dispensed with larger diameters, this results in an unnecessary loss of fluid that is not effectively put to use, which is a particular disadvantage when the fluid contains an active substance.